Perhalocarbon compounds and method of preparing them



United States Patent PERHALOCARBON COMPOUNDS AND METHOD OF PREPARINGTHEM William T. Miller, Ithaca, N. Y.

No Drawing. Application December 16, 1952, Serial No. 326,357

17 Claims. (Cl. 260-566) This invention relates to perhalocarboncompounds and the method of preparing them. In one aspect, the inventionrelates to the production of functional derivatives of unsaturatedperhalocarbons. In another more particular aspect, the invention relatesto the production of perhalovinyl compounds by intermolecularreplacements of allylic halogens. This invention is acontinuation-inpart of my prior and co-pending application Serial No.601,387, filed June 25, 1945, now abandoned, and a division of my priorand co-pending application Serial No. 198,498, filed November 30, 1950,now issued as U. S. Pat. No. 2,691,036.

It has been found that perhalocarbon compounds and their derivatives areof value in various industrial applications such as protective coatingcompositions, electrical insulation, dielectrics, lubrication,refrigeration and the like. Typical of these perhalocarbons are theperfluorocarbons and chloro-derivatives of perfluorocarbon compounds,which may be prepared by the dimerization and addition reactions offluorine with monoand diolefins, by methods such as thermal reactions ofperhaloolefins or by other methods. The principal type products obtainedfrom reaction between fluorine and perhalo ethylenes are the simple ornormal addition product and the dimer addition product. is important inthat it leads to the formation of higher molecular weight compounds fromlow molecular weight olefins. An example of such reaction, is thefluorination of difluorodichloroethylene at a temperature between about70 C. and about -75 C. to give a 40% yield of the dimer addition product1,2,3,4-tetrachloroperfluorobutane. Byproducts from this fluorinationreaction of CFC1=CFC1 are mainly butanes containing up to 6 chlorineatoms and ethanes containing from 1 to 4 chlorine atoms. Nearlyquantitative conversion of the dimer C4CI4F6 into perfluorobutadicue-1,3has been accomplished by dechlorination with zinc dust under improvedconditions for isolation and recovery of this product.Perfluorobutadiene and the perfluorochlorobutadienes prepared in thisway may be converted into a variety of perfluoro products byfluorination and polymerization procedures. Dechlorination of the dimeraddition product of CFCL=CFCl (CFzClCFClCFClCFzCl) with zinc dust anddioxane solution may be carried out so as to give substantial yields of1,4-dichloroperfluorobutene-Z (CFzClCF =CFCF2C1) along withperfluorobutadiene-1,3.

Using a Pyrex reactor tube 1" in diameter heated over a1 section toa-maximum temperature of 550560 C., trifluorochloroethylene passingthrough this reactor at the The dimerization reaction a 2,751,414Patented June 19, 1956 rate of 30-40 grams per hour reacts to give thefollowing approximate amounts of principal products:

0 FOlg-C F=o F2 15-25% 0120M: F=C F; 540%} CFgCl-CFC1CF=CF 35% 65 cF2-oFo1-oFc1-cF, "3075} High boiling residues 5% In other experiments theratio of propenes obtained was approximately one to one.

For example, CF2=CFCl passed at a 45 g./hr. rate through each of six 3 x30 cm. Pyrex glass reactor tubes of a small scale pilot plant reactedwhen heated to 550- 560 C. for 15 seconds to give the followingapproximate yields of major products.

These average results were obtained from a total pass of about 20kilograms of CF2=CFCI in three units with an average conversion of about70%. At higher temperatures, the proportion of propenes in the reactionproduct is increased.

It will be noted that among the olefim'c compounds prepared by the abovemethods, are those which contain allylic halogen, that is, a halogenatom which is bonded to a carbon atom adjacent to a doubly bonded carbonatom, as exemplified by the compound CF2=CFCF2C1 in which the chlorineatom is referred to as theallylic chlorine, and is more reactive thanthe fluorine atoms attached to the same carbon atom. In perfluorounsaturated compounds, allylic fluorine atoms are also more reactivethan the fluorine atoms in the corresponding saturated compound.

It is, therefore, an object of the present invention to producefunctional derivatives of unsaturated perhalo compounds.

Another object of the invention is to produce functional derivatives ofunsaturated perhalo compounds by a method of intermolecular replacement.

A further object of the invention is to produce perhalovinyl compoundsby intermolecular replacements of allylic halogens.

Other objects and advantages of the invention will become apparent fromthe following more detailed disclosure.

It has now been found that allylic halogen in perfluoro compoundscontaining fluorine may be preferentially replaced to produce functionalderivatives of unsaturated perhalo compounds, which contain elementsother than carbon and halogen, by reaction with reagents such as ammoniaand amines, as more fully hereinafter described.

The functional derivatives of unsaturated perhalocarbons produced by themethod of this invention are particularly useful as syntheticintermediates for the production of other perhalocarbon derivatives ofrelatively low molecular weight and as monomers for polymerization toform materials of relatively high molecular weight which are useful aslubricants, coating compositions and the like.

It has thus been found that perhaloallyl compounds may be reacted withammonia and amino derivatives to produce a variety of useful halocarbonderivatives, such as perhalo acrylonitriles. These reactions involve theprogressive replacement of allylic halogens with nitrogen or anitrogen-containing grouping, by splitting out the hydrogen halidebetween the hydrogens on the ammonia or amine molecule and the allylichalogens of the allyl perhalocarbon with the formation of correspondingnitrogen bonds. Three hydrogens are available for reaction in the caseof ammonia, and the resulting product is a nitrile. For example,perfluoroacr ylonitrile may be prepared from perfluoro allyl chlorideand ammonia. This reaction is indicated, in part, by the followingequation:

Another type or reaction for the preparation of perhalo acrylonitrilesin accordance with the present invention, is indicated in part by thefollowing equation:

. The reactions between allylic perhalo compounds and ammonia or aminesto yield the products of the present invention, may be represented asfollows:

where: X is a chlorine or fluorine; Y is fluorine, chlorine, bromine oriodine; R is an alkyl grouping such as CH3, CHsCHz or (CH3)2CH and thelike; or an aryl grouping such as phenyl or naphthyl grouping. However,alkyl groupings are preferred. The alkyl (R) groupings may be the sameor diflerent in Reaction 3 above; 'Compounds formed by the progressivereplacement of allylic halogen with the formation of correspondingcarbonnitrogen bonds, as illustrated by the above equations, are termedperhalovinyl compounds and are to be understood as being derived fromunsaturated allylic perhalocarbons by the method of this invention.

As examples of the ammonia or amino derivatives that may be employed incarrying out the above reactions are pure ammonia; alkyl amines such asmethylamine, ethylamine, dimethylamine; and aryl amines such as aniline,toluidine, and methylaniline. In carrying out the replacement reactionbetween the unsaturated perhalocarbon and the ammonia or amine reagent,in accordance with theequations indicated above, the reagents arepreferably employed in a suitable solvent. The solvent is preferably ina non-aqueous condition. Thus, the reagent may be present in suchsolvents as acetone, benzene or an ether. Other suitable solvents may bechosen from the group comprising pyridine and other tertiary amines,dioxane, dibutyl ether and other ethers; In any given case the solventis chosen to facilitate subsequent separation of thedesired reactionproducts. Therefore, the solvent chosen is preferably one which isreadily separable by distillation from the reactants and reactionproducts.

The reaction between the unsaturated perhalocarbon, containing theallylic halogen, and the ammonia or amino reagent is carried out in asuitable mixing vessel with suflicient stirring to insure thoroughmixing, so that the halogens to be replaced by reaction with the ammoniaor amine will, in general, be obtained as an ammonium type saltprecipitate as indicated by the reactions shown above. An appreciableexcess of free ammonia or amine product and other components present.

is preferably avoided by the addition of the reagent to the halide at arate comparable to or less than the rate of reaction. The reaction iscarried out at atmospheric pressure and at a temperature between aboutl0 C. and about C., with a temperature between about 0 C. and about 150C. being preferred. Following complete admixture and reaction betweenthe unsaturated perhalocarbon starting material and the reagent, thereis obtained a mixture comprising the desired product, namely, theperhalovinyl compound, as defined above, in the solvent and ammoniumsalts corresponding to the halogen replaced, in suspension or partiallydissolved depending upon the solvent employed. This mixture is nextsubjected to distillation in order to separate the desired ammoniumsalts may be separated by filtration before distillation to minimizesuper-heating and bumping in the distillation vessel. Where higherboiling products are obtained as a result of the aforementionedreactions, 'isolation may be accomplished by filtering off or by washingout with water the ammonium halidesalts formed in the reaction, andsubsequently drying and vacuum-distilling the desired products. I

The following examples will serve to illustrate some of the types of theperhalovinyl compounds obtainable and the method of preparing themaccording to the present invention. 1

Example I One-half mol, 83.2 grams of 3-chloroperfluoropropene(CF2=CFCF2C1), was dissolved in approximately 500 cc. of anhydrousdioxane contained in a l-liter threenecked flask. The flask was fittedwith a gas addition tube to extend just above-the liquid level andprovided with a mechanical device which made it possible to clear thetube if solids accumulated at the opening, a Herschberg-type mechanicalstirrer, such as is described and illustrated in OrganicSyntheses-Collective Volume II (by A. H. Blatt, page 117, Figure 4JohnWiley and Sons, Inc., N. Y., 1943), with a gas-tight shaft seal and anicewater cooled reflux coudenser surmounted by a dry-ice cooled refluxcondenser. The stirrer was started and'the mixture was maintained atgentle reflux. Dry ammonia gas contained in a small steel cylinder wasfed into the reaction flask at such a rate that appreciable condensatedid not form on the dry-ice cooled condenser. The rate of ammonia flowwascontrolled by a needle-valve and a flowmeter filled with alightpetroleum-oil. The oveall consumption was checked periodically byweighing the cylinder, which was mounted on a balance and connected tothe reactiousystem with a flcxibletube. halide saltsprecipitated as'thereaction proceeded. A total of 34 grams of ammonia (2 mols) was passedinto the'reaction mixture. The-ammonia was added at such a rate that itwas used up approximately as fast as added and momentary excess ofammonia avoided as-far as possible. After addition of the ammonia, themixture was stirred for an additional hour and then distilled directly,using oil bath heating, with the stirrer operating after replacing thereflux condenser with a short-packed column and distillation head. Afraction, having a B.-P. of- 6.5 C. to 35 C., was collected whichconsisted essentially of a small quantity of recovered startingmaterial, S-cldorcperfluoropropene, and the desired end-product,perfluoroacrylonitrile, CFrrCFCN. The prefluoroarylotion through aneflicient column.

If desired, the

Ammonium Example II In accordance with the procedure described inExample'I above, chloroperfluoroacrylonitrile,

having a B. P. of 62 C. to 65 C., was prepared from CF2=CC1CFzCl(2,3-dichloroperfluoropropene-1 Example 111 In another preparation ofperfluoroacrylonitrile,

CF2=CFCN similarly carried out according to the procedure indicated inExample I above, anhydrous pyridine was employed as the solvent and onlyone mol of ammonia was added to the reaction mixture. It was found thatthe greater solubility of the pyridonium salts formed in the reaction,facilitated stirring and the maintenance of good heat control. It isthus shown that when a tertiary amine such as pyridine is utilized as asolvent, only one mol of the reactive ammonia or primary or secondaryamine is required, inasmuch as the tertiary amine combines with thehydrogen halide formed in the reaction. This reaction is indicated asfollows, in which proper substitutions for X and Y may be made inaccordance with the equivalents previously indicated.

pyridine CFFCXCF Y NHi Example IV CF2=CC1CF2C1 (2,3dichloroperfluoropropene 1) prepared by the pyrolysis of CF2=CFCl(fraction B. P. 3545 C.) was slowly added to diethyl amine withstirring. A rapid exothermic reaction occurred and a yellow crystallinesolid was formed. The solid on treatment with neutral, acidic, or basicaqueous solutions gave an oil which was insoluble in concentrated HCland heavier than water. When it was distilled a fraction boiling at204-206 C. at atmospheric pressure was obtained. The distillate wascolorless and had a sharp narcotic odor.

I claim:

1. A process for the allylic replacement of an unsaturated perhalocarbonwhich comprises: reacting an unsaturated perhalocarbon having a firstunsaturated carbon atom containing only fluorine halogen substitutiononce removed from an allylic carbon atom containing a fluorinesubstituent, and a second unsaturated carbon atom containing halogensubstitution selected from the group consisting of fluorine and chlorinebetween said first unsaturated carbon atom and said allylic carbon atom,with a lower alkyl amine, whereby allylic halogen is replaced with theformation of corresponding carbon-nitrogen bonds to produce a reactionmass comprising the corresponding perhalovinyl compound derived fromsaid unsaturated perhalocarbon.

2. The process of claim 1 wherein said reagent is methylamine.

3. The process of claim 1 wherein said reagent is diethylamine.

4. A process for the allylic replacement of an unsaturated perhalocarbonwhich comprises: reacting an unsaturated perhalocarbon having a firstunsaturated carbon atom containing only fluorine halogen substitutiononce removed from an allylic carbon atom containing a fluorinesubstituent, and a second unsaturated carbon atom containing halogensubstitution selected from the group consisting of fluorine and chlorinebetween said first unsaturated carbon atom and said allylic carbon atom,with a lower alkyl amine, in a non-aqueous solvent, whereby allylichalogen is replaced with the formation of corresponding carbon-nitrogenbond to produce a reaction mass comprising the correspondingperhalovinyl compound derived from said unsaturated perhalocarbon.

5. The process of claim 4 wherein the solvent is acetone.

6. The process of claim 4 wherein the solvent is benzene.

7. The process of claim 4 wherein the solvent is an ether.

8. The process of claim. 4 wherein the solvent is pyridine.

9. The process of claim 4 wherein the solvent is dioxane.

10. A process for the allylic replacement of an unsaturatedperhalocarbon which comprises: reacting an unsaturated perhalocarbonhaving a first unsaturated carbon atom containing only fluorine halogensubstitution once removed from an allylic carbon atom containing afluorine substituent, and a second unsaturated carbon atom containinghalogen substitution selected from the group consisting of fluorine andchlorine between said first unsaturated carbon atom and said allyliccarbon atom, with a lower alkyl amine, at a temperature between about 10C. and about 150 C., whereby allylic halogen is replaced with theformation of corresponding carbonnitrogen bonds to produce a reactionmass comprising the corresponding perhalovinyl compound derived fromsaid unsaturated perhalocarbon.

11. A process for the allylic replacement of an unsaturatedperhalocarbon which comprises: reacting an unsaturated perhalocarbonhaving a first unsaturated carbon atom containing only fluorine halogensubstitution once removed from an allylic carbon atom containing afluorine substituent, and a second unsaturated carbon atom containinghalogen substitution selected from the group consisting of fluorine andchlorine between said first unsaturated carbon atom and said allyliccarbon atom, with a lower alkyl amine, at a temperature between about 0C. and about C., whereby allylic halogen is replaced with the formationof corresponding carbon-nitrogen bonds to produce a reaction masscomprising the corresponding perhalovinyl compound derived from saidunsaturated perhalocarbon.

12. A process for the allylic replacement of an unsaturatedperhalocarbon which comprises: reacting an unsaturated perhalocarbonhaving a first unsaturated carbon atom containing only fluorine halogensubstitution once removed from an allylic carbon atom containing afluorine substituent, and a second unsaturated carbon atom containinghalogen substitution selected from the group consisting of fluorine andsaid allylic carbon atom, with a lower alkyl amine, in a non-aqueoussolvent at a temperature between about l0 C. and about C., wherebyallylic halogen is replaced with the formation of correspondingcarbon-nitrogen bonds to produce a reaction mass comprising thecorresponding perhalovinyl compound derived from said unsaturatedperhalocarbon, solvent and lower alkyl amine; separating the lower alkylamine from said reaction mass; and separating said perhalovinyl compoundfrom the remainder of said reaction mass.

13. A process for the allylic replacement of an unsaturatedperhalocarbon which comprises: reacting an unsaturated perhalocarbonhaving a first unsaturated carbon atom containing only fluorine halogensubstitution once removed from an allylic carbon atom containing afluorine substituent, and a second unsaturated carbon atom containinghalogen substitution selected from the group consisting of fluorine andchlorine between said first unsaturated carbon atom and said allyliccarbon atom, with a lower alkyl amine, in a non-aqueous solvent at atemperature between about 0 C. and about 100 C., whereby allylic halogenis replaced with the formation of corresponding carbon-nitrogen bonds toproduce a reaction mass comprising the corresponding perhalovinylcompound derived from said unsaturated perhalocarbon, solvent and loweralkyl amine; separating lower alkyl amine reagent from said reactionmass; and

V 7 separating said perhalovinyl compound from the remainder of saidreaction mass. V

14. A process for the allylic replacement of an unsaturatedperhalocarbon which comprises: reacting an unsaturated perhalocarbonhaving the general composition CFz CXCFzY, with a lower alkyl amine,wherein aperhalovinyl compound is produced having the generalcomposition CF2=CXCF=NR, and wherein X is a member of the groupconsisting of chlorine and fluorine, Y is a halogen and R is a loweralkyl group.

15. A process for the allylic replacement of an unsaturatedperhalocarb'on which comprises: reacting an unsaturated perhalocar'bonhaving the general composition CF2=CXCF2Y, with a secondary lower alkylamine wherein a perhalovinyl compound is produced having the 8 generalcomposition CF=CXCF2NR2, and wherein X is a; member of the groupconsistingof chlorine and fluorine, Y is a halogen andeach R is a loweralkyl group.

16. A perhalovinyl compound having the general composition CF2=CXCF=NR,wherein X is a member of the group consisting of chlorine and fluorineand R is a lower alkyl group. i g

17. A perhalovinyl compound having the general composition CF2=CXCF2NR2, wherein X is a member of the group consisting of chlorineand fluorine and each R is a lower alkyl group.

2,172, 22 Tamele Sept. 12, 1939

1. A PROCESS FOR THE ALLYLIC REPLACEMENT OF AN UNSATURATED PERHALOCARBON WHICH COMPRISES: REACTING AN UNSATURATED PERHALOCARBON HAVING A FIRST UNSATURATED CARBON ATOM CONTAINING ONLY FLUORINE HALOGEN SUBSTITUTION ONCE REMOVED FROM AN ALLYLIC CARBON ATOM CONTAINING A FLUORINE SUBSTITUENT, AND A SECOND UNSATURATED CARBON ATOM CONTAINING HALOGEN SUBSTITUTION SELECTED FROM THE GROUP CONSISTING OF FLUORINE AND CHLORINE BETWEEN SAID FIRST UNSATURATED CARBON ATOM AND SAID ALLYLIC CARBON ATOM, WITH A LOWER ALKYL AMINE, WHEREBY ALLYLIC HALOGEN IS REPLACED WITH THE FORMATION OF CORRESPONDING CARBON-NITROGEN BONDS TO PRODUCE A REACTION MASS COMPRISING THE CORRESPONDING PERHALOVINYL COMPOUND DERIVED FROM SAID UNSATURATED PERHALOCARBON. 